A cable lock may also be used as an anti-tampering seal device (hence, the term “cable lock and seal device” is used) whereby the cable needs to be cut to break the seal and open the lock. A typical prior art cable lock and seal device is disclosed in European Patent No. EP-0,630,450-B1 (Blair Security Products). In this prior art device, a spring biases a locking wheel against the cable inserted into a straight passageway. The locking wheel is guided by a ramp up to passageway such that insertion of the cable will push locking wheel down the ramp and eases the wheel's engagement against the cable and allow the cable to continue to be inserted to tighten the shackle or to reduce cable slack. Withdrawing the cable, however, would result in the frictional engagement of locking wheel being pushed up the ramp into the passageway, thus locking and preventing the cable from being withdrawn.
When used in heavy-duty applications such as locking and sealing container doors, the device is often subject to heavy stress and the cable being tugged harshly by truck operators and movers as well as by the heavy container doors the devices are supposed to lock. As a result, the locking wheel is often pushed up the ramp into the passageway to engage the cable beyond frictional engagement. The excess force in repeated tugging or pulling the cable in withdrawal direction thus results in the locking wheel teeth biting and shearing into the cable threads resulting in individual cable threads being cut or frayed.
Relevant to the manner in which the locking wheel engages and locks the cable is the design or configuration of teeth on the periphery of the wheel. As shown in International Published Application No. WO 2001/38756 (Bloxwich Engineering) different teeth configurations may be provided to engage the longitudinal surface profile of the cable's braided strands. In U.S. Pat. No. 4,640,538 (Brammall), the teeth are simply provided to engage the individual strands of thread of the bundled and braided cable regardless of the bundles' profile and twist. In U.S. Pat. No. 6,131,969 (Natkins), the teeth are not provided in form of a locking wheel but in a linear row and with increasing height to narrow down to tighten upon the cable. The teeth profile are in the form of caliper-like jaws within which two bundles of a 7-bundle braided cable may be grasped and locked. None of the above prior art cable engaging and locking means discloses a teeth design which engages both individual strands and collective bundle of strands that are braided to form the cable.
Another aspect to be considered is the cable passageway in the device. Most of the prior art devices, including EP-0,630,450-B1, provide for the passageway to be marginally fit for the cable to pass through. Such a straight and fitting passage might allow for a straight pick attack in which a slim pick may be inserted along the engaged cable to reach and push locking wheel away or downwardly to ease the locking engagement and thus loosen the cable and allowing it to be withdrawn or reversed its insertion.
From the above described disadvantages of the prior art, it would be desirable for a lock and seal device to have a cable engaging mechanism which limits the shear by the locking wheel on the cable. It would also be desirable that the cable surface engaging means of the locking mechanism be configured such that its teeth or projections engage the longitudinal surface profile of the cable. It would further be advantageous to provide for features on the cable passageway that guard against picking to loosen the locking wheel's engagement and unlock the cable.